Apparatus for analyzing wave bands



May 29,1945. E K NT 2,377,242

APPARATUS FOR ANALYZING WAVE BANDS Filed July 12, 1943 ,Zigz

Patented May 29, 1945 UNITED SjlATES PATENT OFFICE 2,371,242 a APPARATUS FOR ANALYZING wave mums Earle L. Kent EIkhai-t, Iml, allilnor to 0. G.

Conn, Ltd., Elkl lart, 11141., a corporation of Indi- Application July 12, 1948, Serial No. 494,347

-1 1 Claims. (01. 118-6) This invention relates to apparatus for analyzing wave bands and more particularly to' the analysis, transmission and reception of composite waves containing a series of frequencies.

One of the objects of the invention is to pro vide a visible indication of the frequencies present in a composite wave.

Another object of the invention is to provide apparatus by which -a visible line such as a picture or picture element-can be transmitted, received and reproduced as a whole.

Still another object of the invention is to provide apparatus in which vibrations or oscillations can be utilized to cause separation of a light beam in the manner of a prism to indicate the frequencies present in the vibrations.

The above and other objects and advantages will be more readily apparent from the following description when read in connection with the accompanying drawing, in which- Figure 1 is a diagrammatic view of apparatus for transmitting, receiving and reproducing a visible line;

Figure 2 is an enlarged section of a portion of the receiving apparatus;

Figure 3 is a similar view' of a portion of the transmitting apparatus;

Figure 4 is a horizontal section of Figure 2 on the line 4-4 of Figure 2; and I Figure 5 is' a similar section on the line 55 of Figure 2. H

The present invention may be utilized to produce a visible indication of substantially any desired type of composite wave and i particularly useful for the television transmission of pictures or picture elements in the form of a complete line. The invention will be described hereinafter in connection with such a television apparatus although it will be understood that its uses are not limited thereto.

The transmitting apparatus includes a fluid prism as shown more particularly in Figure 3 which comprises a housing or casing Ill formed with legs ll and I2 connected at an acute angle and having a diffraction grating at their junction. The housing is adapted to contain a column of fluid, preferably a clear liquid such as carbon tetrachloride, although other fluids could be used if desired. At the outer end of the leg ii there is mounted a crystal H which is adapted to set up a'series of oscillations in the fluid which pass therethrough onto the diffraction grating l3. Preferably, a screen I5 is mounted in the leg ll having a transverse slot therein to offer a, line which is similar to the prism l0.

disperse the oscillations so that they will be distributed through the liquid column in the leg l2 according to their respective frequencies, the lowest frequencies being directed to one side of the columnand the highest frequencies to the opposite side with intermediate frequencies uniformly distributed between the two sides. The oscillations passing through the leg l2 are reflected by a rigid closure It for the leg to create a series of standing waves in the leg.

The oscillations may be produced in any one of a number of ways, as for example, from the noise produced by thermal agitation or by shot effect. In the apparatus shown in Figure 1, the crystal is caused to oscillate by a generator I1 and which is connected through an amplifier l8 to the crystal. The generator supplies a continuous spectrum of frequencies in a given band, for example from 5 to 5.5 megacycles.

A line of light of varying density is directed transversely through the fluid column, the density variations corresponding to the light and dark spots in the line to be transmitted. Various sys. terms such as lenses or moving mirrors maybe provided to produce such a line which may move across the slot to scan a picture and in the example shown a light source 20 directs light through a slotted screen and a transparent film 22 through the slots 2| in the leg l2.

The light beam passing through the slots 2| normally falls on a bar or rod 23 but the standing waves diffract the light so that it will pass the bar twice in each cycle. The light so passing is picked up by a light sensitive apparatus such as an elongated photo cell 24 which will have a composite output containing a mixture of frequencies corresponding to the locations in the line of light spots. This output may be amplified in an amplifier 2'5 and transmitted by an antenna 26 or may be used to'modulate a carrier wave which is transmitted.

The signal transmitted by the antenna 26 is a composite wave containing frequencies in the band corresponding to the location of the light spots in the line to be transmitted. It will be understood that this line may be one element of a picture or may, if desired, be an entire picture transformed into a single line by a suitable mirror system. The wave is received-by an antenna 21 and is amplified by an amplifier 28 which is connected to a crystal 3| in one leg of a prism 32 The prism 32 is shown in detail in Figure 2 and parts therein corresponding to identical parts of the prism l0 source of oscillations. The grating functions to d indicated by the Same reference numerals.

In the prism 32 the oscillations are directed against the diflraction grating 13 and are dispersed thereby through the fluid in the leg I! to cause variations in density of the fluid at locations across the column corresponding to the spacing of the frequencies in the band. The oscillations are absorbed by absorptive material 33 in the outer end of the leg l2 which may be cork or the like.

A light source 34 mounted adjacent the prism 32 directs a continuous beam of light through the slots 21 in the leg l2 of the prism and in the absence of oscillations the beam is focused on a bar or rod 35. When oscillations are present in the column, that part of the column acts as a grating to diflract the beam of light so that it will pass the bar or rod 35 at points across the beam corresponding to the location of the oscillations. Since the degree of diifraction depends upon the strength of the oscillations at any given point, the amount of light which passes will be proportional to the strength of the oscillations at that point. The light is collected by a lens 36 which focuses the beam on a screen 31 to give a visible indication of the frequencies present in the band picked up by the antenna 21. This light system is shown more particularly in Figures 4 and which indicate the light source 34 having a lens 38 to focus its rays on the slots 2| in the leg l2. From these figures, it will be seen that the light passes through the slots in the form of a band, portions of which may be intercepted by the bar while other portions are focused by the lens 36 on the screen 31.

To obtain a visual indication of the frequencies present in a composite wave or wave band, an optical wedge may be used in place of the screen 31 of the receiving apparatus. By observing a wedge of this type the frequencies and their respective amplitudes present in a composite wave or wave band may readily be observed. Such an apparatus would be of particular value in analyzing waves.

with the system as described it will be seen that a complete line can be transmitted. received and reproduced without being broken up into separate points so that a much greater definition is possible than with a point by point system. Furthermore, the phase response of the system is not as critical as with a point by point system and all power radiated by the transmitter is c rrying information. In addition to transmission of images in the manner described, the receivin part of the apparatus can be utilized to analyze waves of diflerent types by obtaining a visible indication on the screen-31 or on an optical wedge of the several frequencies present in a complex wave. It will, therefore, be understood that the scope of the invention is not limited to the sp ciflc apparatus described nor otherwise by the terms of the appended claims.

What is claimed is:

1. Apparatus for analyzing a band of frequencies comprising a housing adapted to contain a fluid column, means adjacent one end of the housing to produce a series of oscillations in the column, a diffraction grating in the housing to disperse the oscillations through the column, means to direct a flat beam of light through the housing transversely across the column, and means adjacent the housing responsive to the varying deflection of diflerent portions of the beam of light.

2. Apparatus for analyzing a band of frequencies comprising a housing adapted to contain a fluid column, means adjacent one end of the housing to produce a series of oscillations in the column, a diffraction grating in the housing to disperse the oscillation through the column, means to direct a flat beam of light through the housing transversely across the column, a bar to intercept portions of the beam which are not deflected, and means beyond the bar to receive portions of the beam which are deflected in passing through the column.

3. Apparatus for analyzing a band of frequencies comprising a housing adapted to contain a fluid column, means adjacent one end of the housing to produce a series of oscillations in the column, a diffraction grating in the housingto disperse the oscillations through the column, means to direct a flat beam of light containing light and dark .spots through the housing transversely across the column, a bar to intercept the beam at times during each cycle of the oscillations, and means beyond the bar responsive to portions of the beam which pass the bar to generate a wave containing frequencies proportional to the locations of the light spots in the beam.

4. Apparatus for transmitting and receiving a visible line containing light and dark spots comprising a housing containing a fluid column, means to generate in the column of fluid a series of oscillations, a diffraction grating in the housing to disperse the oscillations through the column, means to direct a flat beam of light containing light and dark spots through the housing, means to intercept the beam at times during each cycle and to pass the beam at other times, means responsive to the beam to generate a wave containing frequencies proportional to the position of the light SpOtsin the beam, and a receiving apparatus for reproducing the line comprising a housing containing a column of fluid, means responsive to the wave to generate in the column a series of oscillations having frequencies proportional to the frequencies in the wave, a diffraction grating in the housing to disperse the oscillations through the column, means to direct a flat beam of light through the housing so that portions thereof will be deflected by parts of the column in which oscillations are present, means to intercept undeflected portions of the beam, and a screen on which deflected portions of the beam are received.

5. Apparatus for analyzing a band of frequencies comprising a curved housing having two substantially straight legs joined at an angle, a ditiraction grating at the junction of the legs, means at the end of one leg to generate a series of oscillations which pass thru said one leg against the grating and are dispersed thereby through the other leg, said other leg being formed with transverse slit; in its opposite sides, and a light source at one side of said other leg to shine a beam of light through said slits.

6. Apparatus for analyzing a band of frequencies comprising a curved housing having two substantially straight legs joined at an angle, a diffraction grating at the junction of the legs, means at the end of one leg to generate a series of oscillations which pass thru said one leg against the grating and are dispersed thereby through the other leg, said other leg being formed with transverse slits in its opposite sides, a light source at one side of said other leg to shine a beam of light through said slits, and absorptive material stantially straight legs joined at an angle, a

other leg, said other leg being formed with transverse slits in its opposite sides, a light source at one side of said other leg to shine a beam of light through said slits, and a reflective closure plate at the outer end of said other leg to reflect the 10 flat beam of light thru the housing transversely across the column, and means adjacent the housing responsive to the varying deflection of difierent portions of the beam of light.

9. Apparatus for analyzing a band of frequencies' comprising a housing adapted to contain a Q3 fluid column, means adjacent one end of the housing to produce a series of oscillations in the column, means in the housing for systematically dispersing the oscillations thru the column to create pressure Waves in the column, means to direct a beam of light thru the column across the pressure waves, and a plurality of targets adjacent the housing to receive the beam of light after it has passed thru the column, distribution of the light among the targets being a function of the deflection of the beam by the pressure waves.

10. Apparatus for analyzing a band of frequencie comprising means forming a column of a medium which will transmit oscillations in the form of pressure waves, means adjacent one end of the column for producing a series of oscillations therein to create pressure waves, means for systematically dispersing the pressure waves thru the column, means to direct a beam thru the column, and a plurality of targets to receive the beam, the distribution of the beam among the targets being a function of the deflection of the beam by the pressure waves in the column.

11. Apparatus for analyzing a band of frequencies comprising means forming a column of a medium which will transmit oscillations in the form of pressure waves, means adjacent one end of the column for producing a series of oscillations therein to create pressure waves, means for systematically dispersing the pressure waves thru the column, means to direct a flat beam of light transversely across the column whereby portions of the beam will be deflected by the pressure waves and other portions will be undeflected where no pressure waves are present, and a plurality of targets adjacent the column to be illuminated respectively by deflected and undeflected portions of the beam.

EARLE L. KENT. 

